Brake actuating mechanism



Jan. 25, 1955 J. H. MURPHY BRAKE ACTUATING MECHANISM 2 Sheets-Sheet 1 Filed NOV. 8, 1950 INVENTOR. JOHN 1'1- NUEPHY ATTORNEYS Jan. 25, 1955 J. H. MURPHY BRAKE ACTUATING MECHANISM 2 Sheets-Sheet 2 Filed Nov. 8, 1950 INVENTOR. JOHN H- NURPH Y ATTORNEYS United States PatentTO BRAKEACTUATING MECHKNISM zilohn H. Murphy, Detroit;-Mich.," assign'or to' Detroit -D'u'o- :Gript Brake-r Corporation, Detr-oit; Mich'r, a corporation. of Michigan :Applicati0mN0vember 8, 11950,*-Serial Noni-94,689

' 7 CIaimsZI- (Cl. 188 76)- I This. invention relatesbroadly to brakes foriautomotive vehicles. and more: specificallyto improvementsin the design? andassemblyibf the brake shoes, .supports, and actuating mechanism therefor.v

.One .of theiobjects of .the invention- .is to provide .a brake shoesupport. whichlwill allow-the: dismantling :of the brake assembly for the .purpose of lining replacement without. disassembling the wheel.

Another obje'ctof the invention-is to providemounting structure for. theibrake-shoeswhich will permit floatingmovement. for self-alignmentin either the braking or released positions forimuniformmbraking-.action. andv the prevention .of binding. in the event the drumssurfacedeparts from. true .circularLform duel-to manufacturingerror or to expansion or icontractionscaused b'yichanges :in temperature.

A still further object'o'f this invention-is to provide a cam surface on one of the brake shoes for. engagement by the actuating..means..which'. will compensate for the radial difference between .the inner ancLouter shoes and thus'-'obtain tuniformbraking' action-as the actuatingforce is applied.

Anotherobje'ct. of the inventionkis. to construct a .brake mechanism.-which. is economic of manufacture, sturdy of structure, and susceptible. to ready adjustment in compensation'ofweanof thebrake.lining.- p Other objects and.advantagesmore :or less-ancillary to thelforegoing .and the manner. .in which all the various objects-arerealized will appear in thefollowingadescription which, considered in connection with the'accompanying. drawings.v sets ..forth. the Lpreferred embodimentaof the invention.

. Referring to the drawings: I

Fig.:..l is a side. .elevationalaview showingthe-brake assemblylmounted for' operation on -a conventional vehicle brake drum;.v I Fig. 2- is' a.cross-sectional.view;of theactuating assemblyta'ken along-.1ine.2 -If2in Eigl l.=; and.

Figi" 3 is a fragmentary cross-sectional..:viewsof the hinge assembly taken along line 3-3 in Fig. 1.

In Fig.4 the-flangeaof the brake:drum. normal ly found on motor vehicle wheels is designated by the numeral and for the purposesof this description;has a normal forwardrotation in the direction--of-the aI10WS. 'rTh6 flangex-lfl has theusual machinedh'surface ona-tbot-huthe inside and.oi1tside diameters to present true circularlsurfaces to receive the "braking elements. A flangell :for carrying the x brake assembly 'circumscribes the rlvehicle wheel -andf-is rigidly' affix'ed to thenvehicle frame-:(mot shown). .A pair of brackets 12 ahdwslfi'. extend laterally from the frame ll' a'nd toward the 'Wheel on which the drum 10 is mounted. The bracket 12 is disposed between the flange and the axle, and the bracket 13 is located on the side of the flange away from the axle. The brackets 12 and 13 are bored to receive a pin 14 which is parallel to the flange of drum 10 and is held in position by set screw 15.

A pair of hinges 16 and 17 are carried by the pins 14 for shifting movement toward and away from the drum 10. Hinge 16 has a pair of parallel bores, one for receiving pin 14 and the other for receiving pin 18 which is held in position in the hinge by means of set screw 19.

An inner brake shoe 20, having a channel cross-section, has the web curved to follow the radius of the inner surface of the drum 10. A pair of ears 21 at one end thereof are bored to receive pin 18 and hold shoe against movement with drum 10 while providing the necessary articulati'onamv allow' the-jshoe 20 to move toward .and away from.drum.10.- vThe usualbrake lining22 is shown mounted. upon the surfaceof shoe 20 adjacentzflange 10 and .held in position .by ihe rivets-23. A sirn-ilara-brake 'shoe 24h'as a. pair of ears. 25 -drilled-to receive pin. 18 which in cooperation with thehin'ge-JJ holds .shoe- 24 on the: outerperiphery :of drum- 10 and allows a lateral movement therebetweem- Shoe 24 has. brake lining 26 mounted thereon, the shoe: and thelining being curved to :presenta complemental surface -;for bearinge.-against the loutside ofv drum: 10. lhelining-26 is -held-yin place on shoe 24 by the useof rivets 27 passing therethrought The .brake shoes 20. anda24 are normally biasedaway fromflange 10 of the:brake-drum. by the-action of retractor springs v28 which: maintain the. shoes clearof the drum between operating intervals.- -=:A bracket 29: integral with .frame 11 is disposed laterally of drumxli) and car-ries yoke- 30 :in its operable position.--'The yoke 30-is-sub stantially U-shaped having a pair of -legs-31 and 32.

.The leg 31 of yoke .30 is adjacent inner -shoe 20 and leg .in operating.position bykeys 35,-. A- pair.of=rollers36 mountedxfor-rotation on. pins/34 have theirtouter surfaces arcuatein thedire'ctionparallel .to themaxis of: rotation. A hardened pad-.37 in substantially. uni-formtc-rossvsection is mounted-on the innermost surface of the--innerbrake sho'e 20. am.. isengaged-by the inner roller-1-36 in rolling relationship thereto .whenthe brake-assembly is placed in operation. second cam shaped pad-384's mounted on the. outer-Lsurface. of the-outer brake 'shoe =24 -atnd receives the. outerroller. 36 :in rolling relationship thereto as theforce= is .appIiedMto actuatethe-brakesw tThe pacl 38 'hasa form. whieh'zwill minimize the'rtravel-necessary to .applywthe brakeandhalsoato insure-ianaevenbraking pressure. .on both. theinner and outerqshoes 20 and -24 respectively as rollers-:36 aresmoved along their respective tpathsof travel; v

The'yoke 30 .hasa splined- -laterall.yrextending-.-shaft :39 intermediate the legs? .31.. and -;32 in -oPPOSed relation thereto. Shaft .39 .is I integral. with :yoke --30 l andwarries yoke- 30 for rotation. about an. axist-paralleltto legsvfi'l and. .32 vintermediate\rollers 36} The spline-shaft 39 \is mounted: in :aresilienttbearing 40 of rubber -or-similar mater-iahebearing- 4,0 being lodgedim a counter-bore in bracket 29 -and :maintained. therein vby-plate= 541' which is heldinplace .by 'capgscrews 424-. I

uln operation thebrake shoes are broughuinto-contaet vvith .dru m 10 by applying aqrotative force toshaftfiQ. Thi sirorce-v is transmitted through woke-r3040 therollers 36 v.which move. toward the ibrake! shoe; I shafit :39 is rotated. xlFurther, rollers-3.6 movel along the -respective pads" as they travel toward the flange of thezrbrakeydrum. The force applied-to.eachbrakeshoe;therefore; is a functionof the 'rotativel foreelapplied tolshaft -39; since the inner rollenris operating on 1 aconvex 'curvature and the camtl38 is. so tshaped-to overcome thisid-iflierenceu in form and-to insurean equal-forcerbeingiapplied toeaeh=of the inn'ena-nd outer r shoesa The resilientbearing'.40. allows yoke 30.10 aligntitself;- thereby telirni-natingnfaulty operationl duento irregularities .or-changes-dn the relative-yoke positiorr due toidrum -expansioni-acaused byy heatingnt The arcuate'surface on the rollers provides'positive contact when misalignment causes bearing 40 to distort, thus tilting the axis of rotation of the rollers.

By locating the hinge brackets on opposite sides of the center-line of the drum, it is possible to carry the brake shoe in a position in which they are both selfenergizing, when the drum is rotating in a forward direction. Conversely, they are not self-energizing when the drum is rotated in a reverse direction and maximum braking is not required. Self-energization, as used herein, is defined as being the braking pressure applied to the shoes in addition to that pressure produced by the actuating means, the additional pressure resulting from the frictional force along the periphery of the drum cooperating with the brake shoe mounting means to obtain a force component toward the drum which multiplies the total braking effect. The outer shoe 24 is hingedly joined to the frame with the pivot spaced from the surface of the brake drum 10. The frictional force on the brake shoe may be considered to operate at the center of the shoe and the surface of the band engaging the drum. Tension, in the case of the outer shoe, produces a force along a line joining the hinge pin connected to the frame and the center of the shoe. Since this line falls between the pin 18 and the drum, a resultant force is produced tending to move the shoe toward the brake drum. A like result obtains in the case of the inner shoe except that the shoe is compressed throughout its length and the force causes the pin 18 to move toward the inner surface of the drum 10. The hinge mounting allows the brake shoes to move toward and away from the flange in uniform lateral increments along the length of the brake band. Thus, even wear and maximum braking force will be accomplished.

Although the foregoing description is necessarily detailed for completely setting forth the invention, it is to be understood that such specific terminology is not intended to be restrictive or confining, and that such modifications are included that may fairly come within the scope and spirit of the invention as herein claimed.

What is claimed is:

1. A brake assembly comprising a brake drum having a flange, internal and external brake shoes on opposite sides of said flange respectively and engageable therewith, mounting means for shiftably carrying said shoes for movement into and out of engagement with the drum,

a U-shaped member rotatably carried by said means, the

axis of rotation being between and parallel to the legs of the member, a roller on each leg of the member respectively for engagement with the shoes as said member is rotated whereby the shoes are biased toward each other and toward the drum for frictional engagement therewith.

2. A brake assembly comprising a brake drum having a flange, internal and external brake shoes on opposite sides of said flange respectively and engageable therewith, mounting means for shiftably carrying said shoes for movement into and out of engagement with the drum, a U-shaped member rotatably carried by said means, the axis of rotation being between and parallel to the legs of the member, each leg of the member respectively engaging a brake shoe as said member is rotated whereby the shoes are biased toward each other and toward the drum for frictional engagement therewith.

3. A brake assembly comprising a brake drum having a flange, internal and external brake shoes on opposite sides of said flange respectively and engageable therewith, mounting means for shiftably carrying said shoes for movement into and out of engagement with the drum, a U-shaped member rotatably carried by said means, the axis of rotation being between and parallel to the legs of the member, a bearing plate on each shoe respectively, said plates being intermediate the ends of the shoe and opposite the drum engaging portion thereof, each leg of the member respectively engaging a bearing plate as said member is rotated whereby the shoes are biased toward each other and toward the drum for frictional engagement therewith.

4. A brake assembly comprising a brake drum having a flange, internal and external brake shoes on opposite sides of said flange respectively and engageable therewith, mounting means for shiftably carrying said shoes for movement into and out of engagement with the drum, a U-shaped member rotatably carried by said means, the axis of rotation being between and parallel to the legs of the member, a bearing plate on each shoe respectively said plates being intermediate the ends of the shoe and til opposite the drum engaging portion thereof, a roller on each leg of the member respectively for engagement with said plates as said member is rotated whereby the shoes are biased toward each other and toward the drum for frictional engagement therewith.

5. A brake assembly for a motor vehicle comprising a brake drum, internal and external brake shoes engageable therewith, a frame aflixed to said vehicle, a pair of opposed hinges shiftably mounted on said frame, one of said hinges being inside of the brake drum and pivotally joined to the internal shoe and the other hinge being outside of the brake drum and pivotally joined to the external shoe, said internal shoe extending away from the hinge in a direction opposite to the normal rotation of said drum, said external shoes extending away from the hinge in a direction corresponding to the direction of normal rotation of said drum, and actuating means on the frame for shifting said shoes toward and away from said drum.

6. A brake assembly for a motor vehicle comprising a brake drum, internal and external brake shoes engageable therewith, a frame affixed to said vehicle, a pair of opposed hinges shiftably mounted on said frame, one of said hinges being inside of the brake drum and pivotally joined to the internal shoe and the other hinge being outside of the brake drum and pivotally joined to the external shoe, said internal shoe extending away from the hinge in a direction opposite to the normal rotation of said drum, said external shoes extending away from the hinge in a direction corresponding to the direction of normal rotation of said drum, a U-shaped member rotatably carried by said frame, the axis of rotation being between and parallel to the legs of the member, each leg of the member respectively engaging a brake shoe as said member is rotated whereby the shoes are biased toward each other and toward the drum for frictional engagement therewith.

7. A brake assembly for a motor vehicle comprising a brake drum, internal and external brake shoes engageaole therewith, a frame affixed to said vehicle, a pair of opposed hinges shiftably mounted on said frame, one of said hinges being inside of the brake drum and pivotally joined to the internal shoe and the other hinge being outside of the brake drum and pivotally joined to the external shoe, said internal shoe extending away from the hinge in a direction opposite to the normal rotation of said drum, said external shoes extending away from the hinge in a direction corresponding to the direction of normal rotation of said drum, a U-shaped member rotatably carried by said frame, the axis of rotation being between and parallel to the legs of the member, a bearing plate on each shoe respectively said plates being intermediate the ends of the shoe and opposite the drum engaging portion thereof, a roller on each leg of the member respectively for engagement with said plates as said member is rotated whereby the shoes are biased toward each other and toward the drum for frictional engagement therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,511,976 Markham Oct. 14, 1924 1,835,593 Chaustowich Dec. 8, 1931 1,847,828 Gerling Mar. 1, 1932 1,936,569 Bendix Nov. 28, 1933 2,239,977 Rosenberg Aug. 29, 1941 2,265,578 Rosenberg Dec. 9, 1941 2,268,685 Walther Jan. 6, 1942 

